Brake light switch harness melting on 2000 Lincoln Town Car

Thank you for your time. I am a professional technician in Texas and have had a continuing issue with the brake light switch harness melting on this car for a year now. I have replace the switch, harness, and shift interlock solenoid with motorcraft parts and still had the melting issue. I then found a TSB in our software nuber "02-13-6". This states that the harness be replace with kit #2W1Z-14A411-AAA". I ordered the harness from Ford and installed per the bulletin, which in fact states "the harness is polarity sensitive" (I still can't understand this)yet the harness has already started to melt after one week. My local ford dealer has been of no help and other freinds in the industry have not had an issue like this one. Any thoughts from you would be of great help. Starting to get embarrassing. Gary

by in Conroe, TX on November 30, 2009
3 answers 8 comments
ANSWER by on November 30, 2009
Hey Gary, Welcome to RepairPal, good question, and great info. I'm looking at the wiring diagram, and I'm not quite clear on which wire(s) is melting. I see the LG/RD wire from the fuse to the switch, then the LG wire to the Central Junction box. Are these connected correctly (Polarity issue referred to in the TSB?) Is it one or both of these wires? What is the current draw when activating the brake lights?
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COMMENT by on November 30, 2009
Thank you bretb for your response. The wire in question is the LG/RD wire from the fuse panel that continues to melt the harness connector. The current draw is 3.7 amps with the brake pedal applied. The new pigtail has been installed per the directions stated in the TSB. The only difference between the old and new harness is the original harness is made with 18ga. wire and the new one is made from 16ga. wire. I have returned the car to the customer after tightening up the terminals and replacing the stop light switch until I can try to come up with another solution. Thank god for tolerant people in this day and age. If you need more info, I can call on them to come by for further testing. Gary
COMMENT by on December 01, 2009
Gary, It sounds like the 18 gauge wire was not able to handle the current, although it should handle 4 amps without a problem. The fact that the new harness has 16 gauge wire leads me to believe this might be a common problem. Do you think there are some driver habits that are contributing to this? Resting their foot on the brake? Is it possible there is an amperage spike after the brake has been applied for awhile? Anyway, glad to hear they are working with you on this, you sound like a very thorough and professional tech. Keep up the good work, let me know if this fixes this problem, and feel free to ask any other questions! Bret
COMMENT by on December 01, 2009
Thank you for all your help with this issue. After seeing the new harness that Ford sent me per the TSB, I thought the same thing about the gauge of the wire and also felt certain that this would resolve the problem. I will talk to my customer about "his wifes" driving habits to verify. I will also have them stop by for another current draw test to see if there could be a spike after applying the brakes. Thank you again and will let you know the outcome. Gary
COMMENT by on November 28, 2010
Ive had the same issue, now for a while, the cable keeps wearing down from the burn. I just added 10 gauge to the tip the what seems to be original red cable is getting shorter and now it may start from where i attached the 10 gauge, not sure whats the problem. i know the pedal stays up and unless its something thats weared out and the pedal is slightly weighing down to activate the switch, but the brake light doesnt stay on by tis self though. Gonna try switching the cables, the other cable seems to be just fine.
COMMENT by on November 28, 2010
I posted that last one aswell, thank you if anyone has anything on this issue relly annoying. Im going to get the book from my friend too so i may see whats the wiring looking like to test the amperage........ respectfully with humble patience, jose
COMMENT by on March 28, 2011
i have the same melting problem on my 1998. got to switch it again thanks.
COMMENT by on May 03, 2012
I have the same issue, the wires to the break switch get hot and melt everything. Does anyone know what causes this? I replaced the break light switch but the wires keep getting hot.
COMMENT by on August 05, 2013
did anyone ever get a real solution to this problem ? i need help i have did all of this still melting
ANSWER by on December 13, 2013
You need to wire in a relay....http://www.lincolnsonline.com/tech/00114.html
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ANSWER by on June 03, 2015
I know this post is old, but I had the same issue with my 98 Lincoln Town car, I kept replacing the switch and harness because it would melt. ( Which I purchased from the auto part store) Before paying the dealership $3++ replace the switch because I already knew how, I purchased the harness and switch directly from the dealership. Following the directions that came with the harness, replaced them both and have not had a problem since.
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